I am having bout of relatively high CPU usage (~20% on quad-core) with 58.0a1 (2017-11-08) (64-bit) (linux version). This is intermittent, and unpredictable (might be happening when I open a new web page, need more data to make the case), and last for a few seconds (10s-20s very roughly estimated).

I looked into this using Gecko profiler, but it shows nothing -- all processes just show they are waiting at poll(), which is normal when the browser is idle (my understanding). The OS System Monitor shows that this is happening in the main process.

This observation is new to me -- not something I observed in previous builds. So anyway, just throwing this out there in case someone else experiences this. I became aware of this through the CPU fan noise.

Hmm, maybe something is happening. For a past few builds I noticed from time to time more sluggishness e.g. loading content icon for a moment when switching from one tab to another... obviously it should be instant except some edge cases with very heavy load on tabs. I thought there was something on the background which is consuming CPU, but I'm not sure now.

gorhill wrote:I am having bout of relatively high CPU usage (~20% on quad-core) with 58.0a1 (2017-11-08) (64-bit) (linux version). This is intermittent, and unpredictable (might be happening when I open a new web page, need more data to make the case), and last for a few seconds (10s-20s very roughly estimated).

I looked into this using Gecko profiler, but it shows nothing -- all processes just show they are waiting at poll(), which is normal when the browser is idle (my understanding). The OS System Monitor shows that this is happening in the main process.

This observation is new to me -- not something I observed in previous builds. So anyway, just throwing this out there in case someone else experiences this. I became aware of this through the CPU fan noise.

gorhill wrote:I am having bout of relatively high CPU usage (~20% on quad-core) with 58.0a1 (2017-11-08) (64-bit) (linux version). This is intermittent, and unpredictable (might be happening when I open a new web page, need more data to make the case), and last for a few seconds (10s-20s very roughly estimated).

I looked into this using Gecko profiler, but it shows nothing -- all processes just show they are waiting at poll(), which is normal when the browser is idle (my understanding). The OS System Monitor shows that this is happening in the main process.

This observation is new to me -- not something I observed in previous builds. So anyway, just throwing this out there in case someone else experiences this. I became aware of this through the CPU fan noise.

I see Nigtly using 10% on my Ryzen 5 1600 while doing absolutely nothing. Something is broken

gorhill wrote:I am having bout of relatively high CPU usage (~20% on quad-core) with 58.0a1 (2017-11-08) (64-bit) (linux version). This is intermittent, and unpredictable (might be happening when I open a new web page, need more data to make the case), and last for a few seconds (10s-20s very roughly estimated).

I looked into this using Gecko profiler, but it shows nothing -- all processes just show they are waiting at poll(), which is normal when the browser is idle (my understanding). The OS System Monitor shows that this is happening in the main process.

This observation is new to me -- not something I observed in previous builds. So anyway, just throwing this out there in case someone else experiences this. I became aware of this through the CPU fan noise.

I see Nigtly using 10% on my Ryzen 5 1600 while doing absolutely nothing. Something is broken

Yes, starting last night, after last night's upgrade, I noticed about 3 to 5 seconds of 25% CPU usage while Firefox is idle. (25% corresponds to a core of this 4-core CPU. I can notice this because 25% heats the CPU enough to kick on the CPU fan.)

It has nothing to do with a throbber because no throbber is running, so it isn't Bug 1406414.

The problem persists after this morning's update. This time, though, it hit about 40% while watching a YouTube video, whereas just watching the video is about 15% CPU.

Antivirus: Norton Security Suite (but with "community watch" turned off; it interferes with Nightly updates). I started using it 8 months ago when Avast Internet Security kept on dropping too many packets for distant websites. (Yes, I know antivirus provided by one's ISP generally has poor reputation, but it proved less troublesome than Avast Internet Security.)

Mark12547 wrote:Yes, starting last night, after last night's upgrade, I noticed about 3 to 5 seconds of 25% CPU usage while Firefox is idle. (25% corresponds to a core of this 4-core CPU. I can notice this because 25% heats the CPU enough to kick on the CPU fan.)

It has nothing to do with a throbber because no throbber is running, so it isn't Bug 1406414.

The problem persists after this morning's update. This time, though, it hit about 40% while watching a YouTube video, whereas just watching the video is about 15% CPU.

Antivirus: Norton Security Suite (but with "community watch" turned off; it interferes with Nightly updates). I started using it 8 months ago when Avast Internet Security kept on dropping too many packets for distant websites. (Yes, I know antivirus provided by one's ISP generally has poor reputation, but it proved less troublesome than Avast Internet Security.)

In my case, no throbbers were involved. First two times I was reading pages that had already loaded and no throbber. This morning I was in the middle of reading a page while another tab in another window was playing a YouTube video and no throbbers were active.

Also, the throbber consuming too much CPU has been reported on really slow machines, with a lot more discussion on the original throbber Bug, where one of the developers had to go out and purchase a laptop as similar as possible as the Reporter of the original throbber Bug so the problem could be reproduced on a slow machine. Discussions on the original throbber Bug got so long that they decided to spawn a new throbber Bug without the hundreds of comments.

I'm going to ask on the Firefox subreddit to see if others have observed the CPU spikes since last night's Nightly update and if we can discover any commonalities.